AndFTP (your FTP client)

A nice light-weight app for doing exactly what I need it to do. It connects to my Synology SFTP server and mirrors the files to the SD Card. I was able to set up a one-way mirror in the free version. If sync is still limited to the pro version, that might mean two-way synchronizations. If you have file names with foreign characters be sure to change the character set in the advanced settings to UTF-8 (or whatever character set you need). Otherwise this app will silently change your filenames to fit within the specified character set. It does not warn you first. The scheduled synchronization feature will suffice. I would prefer an option to trigger synchronization when it gets plugged in for charging.

I use this app to communicate with my modded Nintendo Switch. I've been using FTP for a couple years on my PC to communicate with my Switch which is great and all, but when I just wanna extract a simple file like a video or something, it's annoying to whip out my laptop for that. Now I don't have to worry about that! It's just as fast as my PC but with the benefit of being right on my phone which is very convenient for something like a video I want to share. Great app!

I would love to rate it 5 star. However, I cannot do so because this app just is not reliable for multi-file transfers. Let's see. At relatively random moments, such as when android screen blinks, screen orientation changes or some such, the bulk transfer becomes STUCK. At this point there is no button to make it unstuck, re-continue etc. all I get is a stuck andftp window. There is no working CANCEL or RECONNECT button. And I have to kill andftp and start again. Today, for example, andftp became stuck simply because I laid the phone on my wireless charger. I fully gave up on using FTP protocol and use SCP, which made it better because it eliminated FTP command channel timeouts. However, even with SCP, the app becomes stuck and unusable for completely spurious reasons like screen changes.